1. Field of the Invention
This invention relates to a process for producing a resin product having a bent hollow portion, and a core used in said process. Specific examples of applications of the process and which employs the core include processes for the production of parts for automobiles which have a bent hollow portion, for instance, water a inlet/outlet, pipes such as oil strainers, ducts of induction systems and intake manifolds, in the case where metallic materials for these parts are replaced by resins.
2. Discussion on Related Art
As a process for producing a resin product having a bent hollow portion, such as an S-tube or U-tube, which cannot easily be obtained by molding by means of, for example, a slide core, there is a process which comprises forming a low-melting alloy (for example, melting point of 138.degree. C.) consisting of Zn, Sn, Sb, etc. previously by casting, inserting the formed product into a mold as a core, coating the core with a resin, then heating the core consisting of the low-melting alloy to melt away the same from the resulting molded product, and thereby obtaining a resin product having a bent hollow portion.
However, the removal of the core consisting of the low-melting alloy by melting requires a long heating procedure to melt the alloy, and moreover in a case of mass production, the recovery and re-casting of the melted low-melting alloy is indispensable. Thus, the above process is disadvantageous in that the productivity is very low and that heat deterioration of the resin tends to occur because of an indispensable long heating step at a rather high temperature, which is not desirable for the resin product produced.